As a consequence of relegating stowage of the spare tire to a rearward underslung location certain problems arise relating to accessibility of the air valve stem for inflation and maintenance of proper air pressure. During the course of routinely checking or replenishing the air pressure of said spare tire, one will encounter circumstances requiring strenuous physical activity as it becomes necessary to remove the spare from its carrier or recepticle underneath said motor vehicle to achieve access to the air valve stem; a considerable task involving heavy and cumbersome lifting complicated by a noisome accumulation of road grime contacted during handling procedures. This becomes a cronic inconvenience contributing to the inclination of most to merely neglect maintenance of said underslung spare tire altogether, which in turn creates a potentially adverse situation if said spare becomes deflated due to normal air leakage simultaneously with one of the running tires in service on said motor vehicle becoming defective. This situation is likely to manifest itself in a most untimely manner hypothesizing that the possiblity of such an occurance could present itself in a remote or hazardous location or at the very least result in an inconvenience due to delays in time and expenditures for a road service call. This invention, as hereinafter described, is intended to add a safety factor that will minimize the possibility of occurance of said hazards and inconveniences as its function is to check and, when necessary, replenish the air pressure in a spare tire mounted in said underslung location from a point readily accessible at the rear of said motor vehicle. By virture of the fact that this invention will facilitate the proper maintenance of said underslung spare tire, the motorist will be both encouraged and reminded to check the air pressure in said spare tire routinely and concurrently with the running in-service tires on said motor vehicle.